lately I have noticed a vibration/ rattle in my trans (NV5600) when under acceleration. it's feels kind of like it's lugging, but it not since it only happens 1500 and above. it's worse when towing, but it does do it a little unloaded. it does it in all gears expect 1st and 2nd. it has 32k on it at I started to notice it when I started running a power pup. I have never run it on extreme, so it should not be the clutch.

 

Couple of questions, does it still rattle with the power pup turned off? Has the tranny fluid been changed? I would highly recommend changing the tranny fluid if you haven't already. Pennzoil Synchromesh or Redline MTL is a good replacement.

MikeyB